Using GeoFire with Firebase on Android, but can't find the DatabaseReference Class

I am trying to connect to my Firebase account and make a query using a specific location to see if there are any GeoFire positions in it. For this I am using the official tutorials, but haven't been able to create a Geofire object. Here is what the Tutorial says:

A GeoFire object is used to read and write geo location data to your
Firebase database and to create queries. To create a new GeoFire
instance you need to attach it to a Firebase database reference.